Field of the Invention
The present disclosure pertains to breathing apparatuses, in more detail to anesthesia systems, and even more particularly to anesthesia systems with a volume reflector being part of a breathing circuit of the system. The anesthesia system includes a display with a man-machine interface in the form of a graphical user interface.
Description of Related Art
Re-breathing of previously expired breathing gases into a patient is, amongst other, desired of economic and environmental reasons, specifically to reduce waste of gas that could be used for ventilating a patient connected to an anesthesia system. In particular breathing gas including an anesthetic gas, such as nitrous oxide or xenon, and/or loaded with one or more evaporated volatile anesthetic agents, such as halogenated anesthetic agents, is desired to be returned to the patient in a subsequent inhalation.
Re-breathing in an anesthesia system can be achieved in a number of different ways.
A conventional way is to provide a bag in bottle system, in which expired gas is being received in a bellows, so as to be collected during expiration and to be forced back to the patient in the next inspiration by applying a pressure compressing the bellows from the outside thereof. The driving gas compressing the bellows is separated from the breathing gas by the bellow's membrane. In a bag in bottle system, with visible bellows, the user can clearly see, from the filling state and movement of the bellows, if there is sufficient re-breathed gas available for the next inspiration. Breaths that are too deep mean that the bellows empties completely, and the breath is thus limited, which is also apparent to the user.
An alternative is to provide anesthetic reflectors for the reflection of unused anesthetic gas back towards a patient during following expiration.
For instance in U.S. Pat. No. 4,989,597, an anesthetic reflector in form of an exchanger for open separation is disclosed. The exchanger directly interfaces a ventilator to a patient breathing circuit, and comprises an elongate tube having a reflector volume. The reflector volume is at least of a size being larger than an expected tidal volume of a ventilated patient. The open separation of the gases is resulting from the suitable length of the tube. There is no divider in the open tube, such as a filter or membrane, such as in a traditional bag in bottle system, between the separated gas columns of the ventilator and the patient circuit. This arrangement allows using the reflector volume with a driving gas column virtually moving back and forth in the reflector volume. An adjacent patient gas column is thus alternatingly moving out of the patient circuit into the reflector volume during exhalation, and back into the patient circuit from the reflector volume during inspiration.
Recently, anesthesia apparatuses emerged on the market not having a bellows, but a volume reflector (VR). For instance, the FLOW-I® is a high-performance anesthesia system with a VR designed to meet the many ventilatory challenges within anesthesia, as well as to provide inhalation anesthesia. Owing to the design, there is minimal mixing between the exhaled gas and a driving gas, such as oxygen, in the VR. Another example of a VR is for example disclosed in WO 2010/130290, which is incorporated herein in its entirety for all purposes, of the same applicant as the present disclosure.
Compared to a bag in bottle system, ventilation parameters are improved in a VR system as there is for instance no interfering membrane between the driving gas and the patient circuit. Another advantage is that the system can deliver the requested breathing gas even in case of leakage, e.g. at the tracheal tube. The VR cannot be emptied like a “bag-in-bottle” because driving gas can be supplied continuously.
The VR might in some circumstances by some operators be considered a “black box” hidden in an anesthesia machine. Hence, there is a need to provide operators of VR based anesthesia systems with means for identifying an operational status of the VR in order to facilitate maneuvering of such an anesthesia system and to fully take advantage of its technical capabilities including very economical operation.
In US patent application US2012/0180793A1 a graphical “bellows simulator” is disclosed. The simulator can show in real time that gas that is conveyed to/from the patient in relation to an adjusted tidal volume. The simulator is provided in form of a simple “bellows-like” animation. The animation disclosed in US2012/0180793 A1 is merely an indicator of ongoing ventilation of a patient illustrating inspiration, expiration and respiratory rate. There is no relation of the disclosure in US2012/0180793A1 to a VR or its function. In addition, a graphical illustration of a bellows is undesired for a system having a VR as it may create user confusion if there is a bellows or VR inside the anesthesia system.
Hence, a more efficient man-machine interface for anesthesia systems having a VR would be advantageous.